/*
1+2+3+4+5+..+n 不用循环 乘除 位运算
*/
class Solution
{
    class Sum
    {
    public:
        Sum()
        {
            _sum += _i;
            _i++;
        }
    };
    int Sum_Solution(int n) {
        Sum s[n];
        return _sum;
    }
private:
    static int _sum;
    static int _i;
};
int Solution::_sum = 0;
int Solution::_i = 1;